1. Field of the Invention
The embodiments described herein relate generally to a scanning system for scanning a stream of objects and, more particularly, to a scanning system for scanning a stream of objects that halts and resumes motion.
2. Description of the Related Art
At least some known scanning systems use a computer tomography (CT) system as an imaging section of the scanning system to scan a stream of objects. At least some known volumetric CT systems use helical scan protocols. However, proper image reconstruction using a helical scan protocol with a stream of objects generally requires that objects being scanned move at a constant velocity through the CT system. In at least some applications, for example, in scanning of airline luggage, it may become necessary to halt the stream of objects while being conveyed through the CT system. Such halting is also referred to as “die-back.” After a time period, the scanning of the stream of objects resumes. However, during the halting of the stream of objects, and subsequent acceleration from the halt, the constant speed assumption used for image reconstruction under the helical scan protocol is violated. Accordingly, during halting and acceleration conditions, at least some known CT systems are unable to scan and reconstruct an object within the stream of objects properly.
One known scanning system that includes a CT system does not scan a stream of objects and, as such, does not require the constant velocity assumption to reconstruct images of each object. Accordingly, halting the stream of objects within the scanning system does not adversely affect image reconstruction. However, when a stream of objects is not scanned, throughput of the scanning system may be reduced. Another known scanning system that includes a CT system generates three-dimensional images by scanning a stream of objects. In such a scanning system, when the stream of objects is halted, data acquired regarding an object within the CT system is discarded and the entire object is manually inspected. However, manually inspecting objects may be time consuming and costly.
Accordingly, there is a need for a scanning system that can scan a stream of objects and reconstruct an image of an object within the stream even if the stream of objects is halted and accelerated while the object is within an imaging section of the scanning system and a scan is being performed.